Vehicles, procedures and notification methods

Abstract

A vehicle, a program, and a notification method. The control mode of speed control includes a first control mode in which the actual speed follows the target speed by actively using the brakes, and a second control mode in which the actual speed follows the target speed while suppressing the use of the brakes. The automatic driving system changes a threshold value to a value greater than the value in the first control mode when the control mode is switched from the first control mode to the second control mode, and changes the threshold value to a value smaller than the value in the second control mode when the control mode is switched from the second control mode to the first control mode.

Description

Technical Field

[0001] The present disclosure relates to a vehicle, a program, and a notification method, and more particularly, to a vehicle provided with an automatic driving system that performs speed control for causing an actual speed to follow a target speed, and a suitable program and notification method to be used for the vehicle. Background Art

[0002] When a vehicle is traveling on a long downhill road, the vehicle may reach a brake fade state due to heavy use of the brakes. Japanese Unexamined Patent Application Publication No. 2005-028896 (JP 2005-028896 A) discloses that when a brake fade state is predicted to occur while following travel control is being executed, a condition that causes the need to generate a braking force is suppressed by changing the control characteristics of the following travel control to a control characteristic with a smaller acceleration change. Summary of the invention

[0003] In a vehicle equipped with an automatic driving system, a target speed is set according to an action plan, and speed control is performed so as to cause the actual speed to follow the target speed. When a speed error between the target speed and the actual speed exceeds a threshold value in the speed control, a notification is provided to the driver. The notification to the driver includes, for example, a hands-on request notification requesting the driver to touch the steering wheel, and a transition demand (TD) notification notifying the driver of a request to transfer driving authority from the automatic driving system to the driver.

[0004] When the technology described in JP 2005-028896 A is applied to an autonomous driving system, as the frequency of generating braking force decreases, the followability of the actual speed relative to the target speed decreases. As a result, the number of situations where the speed error between the target speed and the actual speed exceeds the threshold value increases, and the frequency of notifications to the driver also increases. However, in this case, the increase in the speed error between the target speed and the actual speed is temporary to suppress brake attenuation. That is, even when the followability of the actual speed relative to the target speed decreases, such a decrease is within the permissible range as a driver assistance function of the autonomous driving system, and it may not be necessary to provide notifications to the driver. Frequent notifications that are not always necessary may annoy the driver.

[0005] An object of the present disclosure is to provide a technology capable of optimizing the frequency of notification to a driver when the followability of an actual speed relative to a target speed decreases while speed control is performed by an automatic driving system.

[0006] The present disclosure provides a vehicle for achieving the above-mentioned purpose. The vehicle according to the present disclosure is a vehicle equipped with an automatic driving system that performs speed control that causes the actual speed to follow the target speed. The automatic driving system included in the vehicle according to the present disclosure includes at least one memory storing at least one program, and at least one processor connected to the at least one memory. The at least one processor performs the control mode switching process, notification process, first threshold value change process, and second threshold value change process described below by executing at least one program.

[0007] The control mode switching process is a process of switching the control mode of speed control between a first control mode and a second control mode according to the driving condition, the first control mode being a mode in which the actual speed follows the target speed by actively using the brakes, and the second control mode being a mode in which the actual speed follows the target speed while suppressing the use of the brakes. The notification process is a process of providing a notification to the driver when the speed error between the target speed and the actual speed exceeds a threshold value while executing the speed control. The first threshold value change process is a process of changing the threshold value to a value greater than the value in the first control mode when the control mode is switched from the first control mode to the second control mode. The second threshold value change process is a process of changing the threshold value to a value less than the value in the second control mode when the control mode is switched from the second control mode to the first control mode.

[0008] In the vehicle according to the present disclosure, in the second threshold value changing process, the threshold value may be gradually changed to a value smaller than the value in the second control mode. Further, in the first threshold value changing process, the threshold value may be gradually changed to a value larger than the value in the first control mode.

[0009] The present disclosure provides a program for achieving the above-mentioned purpose. The program according to the present disclosure is a program that causes a computer to notify a driver of a vehicle equipped with an automatic driving system that performs speed control to cause the actual speed to follow the target speed when the speed error between the target speed and the actual speed exceeds a threshold. Here, the control mode of the speed control includes a first control mode and a second control mode, in which the actual speed follows the target speed by actively using the brake, and in which the actual speed follows the target speed while suppressing the use of the brake.

[0010] The program according to the present disclosure causes the computer to execute a process of changing the threshold value to a value larger than the value in the first control mode when the control mode is switched from the first control mode to the second control mode. Further, the program according to the present disclosure causes the computer to execute a process of changing the threshold value to a value smaller than the value in the second control mode when the control mode is switched from the second control mode to the first control mode.

[0011] The present disclosure provides a notification method for achieving the above-mentioned purpose. The notification method according to the present disclosure is a method for providing a notification to a driver of a vehicle equipped with an automatic driving system that performs speed control to cause the actual speed to follow the target speed when the speed error between the target speed and the actual speed exceeds a threshold. Here, the control mode of the speed control includes a first control mode and a second control mode, in which the actual speed follows the target speed by actively using the brake, and in which the actual speed follows the target speed while suppressing the use of the brake.

[0012] The notification method according to the present disclosure includes a first step and a second step. The first step is a step of changing a threshold value to a value greater than a value in the first control mode when the control mode is switched from the first control mode to the second control mode. The second step is a step of changing a threshold value to a value less than a value in the second control mode when the control mode is switched from the second control mode to the first control mode.

[0013] According to the vehicle, program, and notification method of the present disclosure, when the first control mode in which the actual speed follows the target speed by actively using the brake is selected as the control mode of speed control, the threshold value is set to a relatively small value. On the other hand, when the second control mode in which the actual speed follows the target speed while suppressing the use of the brake is selected as the control mode of speed control, the threshold value is set to a relatively large value.

[0014] The first control mode is a control mode in which a relatively high target speed following performance is achieved through the active use of brakes. Therefore, the speed error between the target speed and the actual speed is relatively less likely to occur. According to the vehicle, program and notification method of the present disclosure, setting the threshold to a relatively small value makes it possible to suppress the failure of the automatic driving system from being ignored. The second control mode is a control mode in which the target speed following performance is relatively reduced compared to the first control mode while suppressing the use of brakes. Therefore, the speed error between the target speed and the actual speed is relatively easy to occur. According to the vehicle, program and notification method of the present disclosure, setting the threshold to a relatively large value makes it possible to suppress the frequent issuance of notifications that are not always necessary. That is, according to the vehicle, program and notification method of the present disclosure, when the followability of the actual speed relative to the target speed is reduced while the speed control is performed by the automatic driving system, the frequency of providing notifications to the driver can be optimized. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, wherein like numerals represent like elements, and wherein:

[0016] Figure 1is a block diagram showing a configuration of an automatic driving system included in a vehicle according to a first embodiment of the present disclosure;

[0017] Figure 2 is a flowchart showing a method for determining a control mode of speed control performed by an automatic driving system included in a vehicle according to a first embodiment of the present disclosure;

[0018] Figure 3 is a diagram illustrating a problem that occurs when the control mode is switched;

[0019] Figure 4 A diagram showing threshold setting according to the first embodiment of the present disclosure;

[0020] Figure 5 is a diagram illustrating a problem that occurs when the control mode is switched;

[0021] Figure 6 A diagram showing threshold setting according to a second embodiment of the present disclosure;

[0022] Figure 7 is a diagram illustrating a problem that occurs when the control mode is switched;

[0023] Figure 8 A diagram showing threshold setting according to a third embodiment of the present disclosure; and

[0024] Fig. 9 To show Figure 8 Figure 2. Deformation of the threshold settings shown in Figure 2. DETAILED DESCRIPTION

[0025] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, when the quantity, number, amount, range, etc. of each element is mentioned in the embodiments shown below, the concept of the present disclosure is not limited to the quantity mentioned herein unless it has been clearly stated in principle or clearly specified in quantity. In addition, the structures and the like described in the embodiments shown below are not necessarily necessary for the concept of the present disclosure unless it has been clearly stated in principle or clearly specified.

[0026] 1. First Embodiment

[0027] 1-1. Vehicle configuration with autonomous driving system

[0028] Figure 1The block diagram is a diagram showing the configuration of the autonomous driving system included in the vehicle according to the first embodiment of the present disclosure. The autonomous driving system 100 included in the vehicle 10 is an electronic control unit (ECU), i.e., a computer, provided with at least one processor 102 (hereinafter referred to as "processor 102") and at least one memory 104 (hereinafter referred to as "memory 104"). The memory 104 includes a main storage device and an auxiliary storage device. The memory 104 stores at least one program 106 (hereinafter referred to as "program 106") that can be executed by the processor 102 and various data related thereto. When the processor 102 executes the program 106 stored in the memory 104, various functions are implemented in the autonomous driving system 100. The ECU constituting the autonomous driving system 100 may be a group of multiple ECUs.

[0029] If Figure 1 As shown in the block diagram in FIG. 1 , the autonomous driving system 100 includes a system state control unit 110, a surrounding recognition unit 120, an action plan generation unit 130, a speed control unit 140, and a system state notification unit 150 as configurations related to the autonomous driving of the vehicle 10. When the program 106 stored in the memory 104 is executed by the processor 102, the above units are implemented as functions of the autonomous driving system 100.

[0030] The system state control unit 110 is configured to communicate with each of the periphery recognition unit 120 , the action plan generation unit 130 , the speed control unit 140 , and the system state notification unit 150 .

[0031] The surrounding recognition unit 120 uses a recognition sensor (not shown) such as a camera, light detection and ranging (LiDAR) or radar to perform recognition of the surrounding conditions of the vehicle 10 and obtain target information such as the front vehicle, pedestrians, etc. Since the method of obtaining the target information by the recognition sensor is known, its description is omitted here.

[0032] The action plan generation unit 130 generates an action plan for the vehicle 10 based on the map information of the map database, the position information of the vehicle 10 obtained using the Global Positioning System (GPS), and the target information obtained by the surrounding recognition unit 120. The action plan includes a target trajectory for causing the vehicle 10 to travel along a preset driving route and the content of the action plan. The target trajectory is generated as a set having multiple elements consisting of two elements: a target position in a coordinate system fixed to the vehicle 10 and a target speed at each target point. The content of the action plan is the content corresponding to the purpose of the speed control of the automatic driving. The content of the action plan is determined based on driving conditions such as driving at a constant speed, decelerating on a curve, following the vehicle in front, and driving on a long downhill road.

[0033] The speed control unit 140 controls the speed of the vehicle 10 based on the action plan generated by the action plan generation unit 130. The action plan includes a target trajectory. The speed control unit 140 determines a target driving force and a target acceleration so that the vehicle 10 travels along the target trajectory. More specifically, the speed control unit 140 calculates a speed error between a target speed included in the target trajectory and an actual speed of the vehicle 10 measured by a wheel speed sensor, and determines a target driving force and a target acceleration to reduce the speed error.

[0034] The speed control unit 140 performs a control mode switching process for switching the control mode of speed control based on the content of the action plan. The control mode includes a first control mode and a second control mode, and the calculation method for determining the target driving force and the target acceleration according to the speed error is different for each control mode. Specifically, in the first control mode, the target driving force and the target acceleration are determined so that the actual speed follows the target speed by actively using the brake. On the other hand, in the second control mode, the target driving force and the target acceleration are determined so that the actual speed follows the target speed while suppressing the use of the brake. The method for determining the control mode of speed control will be described in detail later.

[0035] The target driving force and the target acceleration determined by the speed control unit 140 are sent to the actuator ECU 300. The actuator ECU 300 controls the driving force and the braking force of the control driving system to achieve the target driving force and the target acceleration. The control driving system includes, for example, a power device such as an electric motor, an engine, and a hybrid system capable of controlling the control driving force, and an electronic brake control system capable of controlling the braking force.

[0036] When the speed error between the target speed and the actual speed becomes large, there is a possibility that the automatic driving system 100 may not be able to continue the automatic driving due to environmental conditions or a malfunction of the automatic driving system 100. Therefore, the speed control unit 140 performs speed control so that the actual speed follows the target speed, and at the same time, performs a manual control request determination and a TD determination based on the speed error between the target speed and the actual speed. The manual control request determination is a determination as to whether to request the driver to perform manual control. The TD determination is a determination as to whether to request the transfer of driving authority from the automatic driving system 100 to the driver (TD).

[0037] In the manual control request determination, the speed control unit 140 compares the speed error with a predetermined manual control request threshold. When the speed error exceeds the manual control request threshold, the manual control request is output to the speed control unit 140 and the system state control unit 110. In the TD determination, the speed control unit 140 compares the speed error with a predetermined TD threshold. The TD threshold is set to a value larger than the manual control request threshold. Therefore, the speed error always exceeds the TD threshold after the speed error exceeds the manual control request threshold. When the speed error exceeds the TD threshold, TD is output to the speed control unit 140 and the system state control unit 110. As will be described in detail later, the settings of the manual control request threshold and the TD threshold are changed depending on the control mode.

[0038] The system state notification unit 150 performs notification processing. Specifically, when the system state control unit 110 receives a manual control request from the speed control unit 140, the system state control unit 110 sends a command to the system state notification unit 150. The system state notification unit 150 receives the command from the system state control unit 110 and outputs a manual control request notification to the meter ECU 200. Similarly, when the system state control unit 110 receives a TD from the speed control unit 140, the system state control unit 110 sends a command to the system state notification unit 150. The system state notification unit 150 outputs a TD notification to the meter ECU 200 in response to the command from the system state control unit 110. The meter ECU 200 is an ECU that controls a display that notifies the driver of the system state.

[0039] 1-2. Method for determining the control mode of speed control

[0040] In the automatic driving system 100, the target speed is set according to the content of the action plan. For example, on a straight road without a front vehicle, following control is performed with the set speed set by the driver as the target speed. On the other hand, when there is a front vehicle slower than the set speed set by the driver, following control is performed with a speed set based on the speed of the front vehicle as the target speed to follow the front vehicle. Even when the front vehicle inserts in front of the vehicle 10, the target speed is set based on the speed of the inserted front vehicle. In addition, on a curved road, there may be a situation where following control is performed with a speed slower than the set speed set by the driver as the target speed so that the vehicle can travel safely on the curved road. Generally speaking, the content of the action plan of the automatic driving system 100 can be classified into content that simply controls the vehicle speed to follow the set speed set by the driver (action plan content 1) and content that controls the vehicle speed to follow the target speed that is changed according to the surrounding conditions (action plan content 2).

[0041] Figure 2 1 is a flowchart showing a method for determining a control mode of speed control performed by the automatic driving system 100. In step S100, it is determined whether following control is being performed to follow a set vehicle speed set by the driver, that is, whether speed control is performed according to the above-mentioned action plan content 1.

[0042] As a result of the determination in step S100, when the speed control is performed according to the action plan content 2 instead of the action plan content 1, step S300 is performed. In step S300, the first control mode is selected as the control mode of the speed control. In the first control mode, the target driving force and the target acceleration are determined so that the actual speed follows the target speed by the active use of the brake. The execution of the speed control in the first control mode enables a high speed following performance relative to the target speed changed according to the surrounding conditions.

[0043] On the other hand, as a result of the determination in step S100, when the speed control is performed according to the action plan content 1, step S200 is performed. In step S200, it is further determined whether the optional condition of the second control mode is satisfied. The action plan content 1 includes the content (action plan content 3) that satisfies the optional condition of the second control mode. In step S200, it is determined whether the action plan content 1 is the action plan content 3.

[0044] In the second control mode, speed control is performed to cause the actual speed to follow the target speed while suppressing the use of the brake. Therefore, when the second control mode is selected, the brake is not actively used, thereby reducing the speed following performance relative to the target speed compared to when the first control mode is selected. Nevertheless, as a case where there is an advantage in selecting the second control mode, for example, a case where the vehicle 10 is traveling on a long downhill road can be exemplified. There may be a situation where extensive use of the brake on a long downhill road may cause a brake attenuation state. However, when the second control mode is selected, the use of the brake can be suppressed, and thus the brake can be suppressed from being placed in a brake attenuation state. An example of action plan content 3 is that the following control on a long downhill road is simply performed to follow the set vehicle speed set by the driver.

[0045] As a result of the determination in step S200, when the optional condition of the second control mode is not satisfied, that is, when the execution condition of the speed control according to the above-mentioned action plan content 3 is not satisfied, step S300 is executed. Step S300 is executed to execute the speed control in the first control mode, so that the speed following performance relative to the target speed can be suppressed from being unnecessarily reduced. On the other hand, as a result of the determination in step S200, when the optional condition of the second control mode is satisfied, step S400 is executed. In step S400, the second control mode is selected as the control mode of the speed control. For example, the selection of the second control mode makes it possible to suppress the brake from being placed in a brake fade state when the vehicle 10 is traveling on a long downhill road.

[0046] 1-3. Threshold setting in each control mode

[0047] Next, we will refer to Figure 3 and Figure 4 The setting of the threshold value in each control mode determined as described above is described. Figure 3 and Figure 4 Each shows an example of a change in speed error over time when the control mode is switched from the first control mode to the second control mode and then switched from the second control mode to the first control mode again. Figure 3 The velocity error shown in Fig. Figure 4 The velocity error shown in varies with time in the same way.

[0048] The speed following performance of the second control mode is reduced compared to the speed following performance of the first control mode. Therefore, the speed error tends to become larger. However, the speed error in this case is temporarily caused to increase to suppress the brake from being placed in a brake attenuation state. Therefore, even when the speed error increases, depending on the degree of the speed error, the increase may be within the allowable range for the driver assistance function of the automatic driving system 100.

[0049] However, when Figure 3 As shown in , if the manual control request threshold is constant regardless of the control mode, then when the control mode is the second control mode, the speed error may easily exceed the manual control request threshold. In this case, frequently providing the driver with unnecessary manual control request notifications may annoy the driver. In addition, assuming Figure 3 As shown in , the TD threshold is constant regardless of the control mode, then when the control mode is the second control mode, the speed error may easily exceed the TD threshold. In this case, although the manual control request notification is sufficient, the TD notification is still provided to the driver, which may cause the driver to perform unnecessary manual driving.

[0050] To resolve the reference Figure 3 The problem described, in the first embodiment, is Figure 4 Each threshold is set as shown in . First, the manual control request threshold is set to be larger in the second control mode than in the first control mode. Specifically, the manual control request threshold in the first control mode is set to X [kph], and the manual control request threshold in the second control mode is set to X + α [kph], which is α [kph] larger than the manual control request threshold in the first control mode.

[0051] The TD threshold is greater than the manual control request threshold, and the TD threshold in the second control mode is greater than the TD threshold in the first control mode. Specifically, the TD threshold in the first control mode is set to Y [kph], and the TD threshold in the second control mode is set to Y + β [kph], which is β [kph] greater than the TD threshold in the first control mode. Y is greater than X, and Y + β is greater than X + α.

[0052] When the control mode is switched from the first control mode to the second control mode by setting each threshold as described above, the manual control request threshold and the TD threshold are respectively changed to values ​​larger than the values ​​in the first control mode. Hereinafter, the processing performed by the automatic driving system 100 is referred to as the first threshold change processing. Specifically, in the first threshold change processing according to the first embodiment, each threshold is increased in the manner of a step function. In addition, when the control mode is switched from the second control mode to the first control mode, the manual control request threshold and the TD threshold are respectively changed to values ​​smaller than the values ​​in the second control mode. Hereinafter, the processing performed by the automatic driving system 100 is referred to as the second threshold change processing. Specifically, in the second threshold change processing according to the first embodiment, each threshold is reduced in the manner of a step function.

[0053] Even when the speed error increases due to switching from the first control mode to the second control mode by increasing the value of the manual control request threshold in the second control mode to be larger than the value in the first control mode, the speed error is suppressed from exceeding the manual control request threshold. With this configuration, it is possible to suppress the driver from receiving notifications that are not always necessary. In addition, increasing the value of the TD threshold in the second control mode to be larger than the value in the first control mode makes it possible to suppress the driver from receiving the TD notification despite the situation that the manual control request notification is sufficient when the control mode is switched to the second control mode.

[0054] 2. Second Embodiment

[0055] Next, a second embodiment according to the present disclosure will be described. However, the configuration of the automatic driving system included in the vehicle according to the second embodiment is the same as that of the first embodiment, and is composed of Figure 1 In addition, in the second embodiment, according to the same method as the first embodiment, Figure 2 The second embodiment is different from the first embodiment in the setting of the threshold value in each control mode.

[0056] Figure 5 and Figure 6 Each shows an example of a change in speed error over time when the control mode is switched from the first control mode to the second control mode and then switched from the second control mode to the first control mode again. Figure 5 The velocity error shown in Fig. Figure 6 The velocity error shown in varies with time in the same way.

[0057] Figure 5 The setting of the threshold values ​​shown in is the setting of the threshold values ​​according to the first embodiment. The manual control request threshold value is set to be larger in the second control mode than in the first control mode. The TD threshold value is larger than the manual control request threshold value, and the TD threshold value in the second control mode is larger than the TD threshold value in the first control mode. By setting each threshold value as described above, even when the speed error increases due to switching from the first control mode to the second control mode, the speed error is suppressed from exceeding the manual control request threshold value, and further the speed error is suppressed from exceeding the TD threshold value.

[0058] However, even when the control mode is switched to the first control mode again, the speed error increased in the second control mode does not converge immediately. Figure 5As shown, when the manual control request threshold is reduced in a step function manner in response to the switch from the second control mode to the first control mode, the speed error temporarily exceeds the manual control request threshold, and therefore, a manual control request notification is issued to the driver. However, when no system failure or the like occurs, the speed error converges as time passes from the switch to the first control mode. Therefore, even when a speed error occurs immediately after the switch to the first control mode, it is desirable to avoid providing a manual control request notification unless the occurrence of the speed error continues for a long time. The same applies to the TD notification made when the speed error exceeds the TD threshold.

[0059] To solve Figure 5 According to the second embodiment, as described in Figure 6 Each threshold value is set as shown in . First, when the control mode is switched from the first control mode to the second control mode, the manual control request threshold value and the TD threshold value are respectively changed to values ​​larger than those in the first control mode by executing the first threshold value change processing. Similar to the first embodiment, in the first threshold value change processing according to the second embodiment, each threshold value is increased in a step function manner.

[0060] Next, when the control mode is switched from the first control mode to the second control mode again, the manual control request threshold and the TD threshold are respectively returned to values ​​lower than those in the second control mode by executing the second threshold value changing process. However, in the second threshold value changing process according to the first embodiment, each threshold value is lowered in a step function manner, while in the second threshold value changing process according to the second embodiment, each threshold value is gradually lowered in a predetermined threshold value gradual change period.

[0061] After the control mode is switched from the second control mode to the first control mode, the speed error increased in the second control mode requires a certain amount of time to converge. According to the second embodiment, after the second control mode is switched from the second control mode to the first control mode, the manual control request threshold is gradually lowered so that the speed error that temporarily increases can be suppressed from exceeding the manual control request threshold. Through this configuration, it is possible to suppress the driver from frequently receiving manual control request notifications that are not always necessary. In addition, the TD threshold is gradually lowered after the control mode is switched to the first control mode, so that it is possible to suppress the driver from receiving the TD notification regardless of the situation where the manual control request notification is sufficient when the speed error increases even after the control mode is switched to the first control mode.

[0062] 3. Third embodiment

[0063] Next, a third embodiment according to the present disclosure will be described. However, the configuration of the automatic driving system included in the vehicle according to the third embodiment is the same as that of the first embodiment, and is composed of Figure 1In addition, in the third embodiment, according to the same method as the first embodiment, Figure 2 The third embodiment is different from the first and second embodiments in the setting of the threshold value in each control mode.

[0064] Figure 7 and Figure 8 Each shows an example of a change in speed error over time when the control mode is switched from the first control mode to the second control mode and then switched from the second control mode to the first control mode again. Figure 7 The velocity error shown in Fig. Figure 8 The velocity error shown in varies with time in the same way.

[0065] Figure 7 The setting of the threshold values ​​shown in is the setting of the threshold values ​​according to the second embodiment. The manual control request threshold value is set to be larger in the second control mode than in the first control mode. The TD threshold value is larger than the manual control request threshold value, and the TD threshold value in the second control mode is larger than the TD threshold value in the first control mode. By setting each threshold value as described above, even when the speed error increases due to switching from the first control mode to the second control mode, the speed error is suppressed from exceeding the manual control request threshold value, and the speed error is further suppressed from exceeding the TD threshold value.

[0066] However, there is a possibility that the speed error has exceeded the manual control request threshold value during the stage of the first control mode, and the control mode is switched from the first control mode to the second control mode while providing the manual control request notification. In this case, when the manual control request threshold value is increased in a step function manner in response to the switch from the first control mode to the second control mode, the speed error falls within the manual control request threshold value, and therefore, the manual control request notification is canceled. The manual control request notification issued to the driver during the first control mode stage is a necessary manual control request notification due to a system failure, etc. Therefore, it is not expected that the manual control request notification will be canceled due to the control mode switching to the second control mode. The same applies to the TD notification made when the speed error exceeds the TD threshold value.

[0067] To solve Figure 7 According to the third embodiment, as described in Figure 8Each threshold value is set as shown in . First, when the control mode is switched from the first control mode to the second control mode, the manual control request threshold value and the TD threshold value are respectively changed to values ​​larger than those in the first control mode by executing the first threshold value change processing. However, in the first threshold value change processing according to the first and second embodiments, each threshold value increases in a step function manner, while in the first threshold value change processing according to the third embodiment, each threshold value gradually increases in a predetermined threshold value gradual change period.

[0068] Next, when the control mode is switched from the second control mode to the first control mode again, the manual control request threshold and the TD threshold are respectively changed to values ​​smaller than those in the second control mode by executing the second threshold change processing. Similar to the second embodiment, in the second threshold change processing according to the third embodiment, each threshold is gradually lowered in a predetermined threshold gradual change period.

[0069] When the speed error occurring during the speed control in the first control mode is not a temporary error but is caused by a system failure, the speed error continues to occur even after the control mode is switched from the second control mode to the first control mode. When the speed error is caused by a system failure, preferably, a manual control request is issued to the driver to prepare for switching from the automatic driving to the manual driving. According to the third embodiment, after the control mode is switched from the first control mode to the second control mode, the manual control request threshold is gradually increased so that the period during which the speed error exceeds the manual control request threshold, that is, the period during which the manual control request notification is provided to the driver is extended. This makes it easier for the driver to notice the manual control request notification and allows the driver to prepare for switching to manual driving. In addition, the gradual increase in the TD threshold after the control mode is switched to the second control mode prolongs the period during which the TD notification is issued to the driver while continuing to issue the TD notification until just before switching to the second control mode. This makes it easier for the driver to notice the TD notification, thereby quickly transferring the driving authority from the automatic driving system 100 to the driver.

[0070] There may be a case where, when each threshold value gradually increases after the control mode is switched from the first control mode to the second control mode, the control mode is switched to the first control mode again within the threshold gradual change period. In this case, for example, each threshold value may be as follows: Fig. 9. When the control mode is switched from the first control mode to the second control mode, it is unknown when it will return to the first control mode next time. Therefore, in a predetermined threshold gradient period, the manual control request threshold changes at a rate of increasing from X [kph] to X + α [kph]. In addition, in a predetermined threshold gradient period, the TD threshold changes at a rate of increasing from Y [kph] to Y + β [kph]. Then, when the control mode is switched from the second control mode to the first control mode within the threshold gradient period, the manual control request threshold is reduced to X [kph] in the predetermined threshold gradient period from that moment on, and the TD threshold is reduced to Y [kph] in the predetermined threshold gradient period.

[0071] 4. Other embodiments

[0072] As the setting of each threshold, in the first threshold change processing, each threshold can be gradually increased in a predetermined threshold gradient period as in the third embodiment, and in the second threshold change processing, each threshold can be reduced in a step function manner as in the first embodiment.

[0073] Furthermore, in the above-described embodiment, a long downhill road is exemplified as a case where the second control mode is selected. However, the second control mode may be selected in other cases.

Claims

1. A vehicle equipped with an automatic driving system that performs speed control such that the actual speed follows a target speed, wherein: The autonomous driving system comprises: at least one memory storing at least one program, and at least one processor connected to the at least one memory; and The at least one processor performs, by executing the at least one program: a control mode switching process for switching the control mode of the speed control between a first control mode in which the actual speed follows the target speed by actively using the brakes and a second control mode in which the actual speed follows the target speed while suppressing the use of the brakes, according to a driving condition, a notification process for providing a notification to a driver when a speed error between the target speed and the actual speed exceeds a threshold value while the speed control is being executed, a first threshold value changing process of changing the threshold value to a value larger than the value in the first control mode when the control mode is switched from the first control mode to the second control mode, and A second threshold value changing process is performed to change the threshold value to a value smaller than the value in the second control mode when the control mode is switched from the second control mode to the first control mode.

2. The vehicle according to claim 1, wherein: In the second threshold value changing process, the threshold value is gradually changed to a value smaller than the value in the second control mode.

3. The vehicle according to claim 1 or 2, wherein: In the first threshold value changing process, the threshold value is gradually changed to a value larger than the value in the first control mode.

4. A computer program product comprising a computer program which, when executed by a processor, causes a computer to perform a notification to a driver of a vehicle equipped with an automatic driving system that performs speed control so that an actual speed follows a target speed when a speed error between the target speed and the actual speed exceeds a threshold, wherein: The control mode of the speed control includes a first control mode in which the actual speed is caused to follow the target speed by actively using the brake, and a second control mode in which the actual speed is caused to follow the target speed while suppressing the use of the brake; and The computer program causes the computer to execute: When the control mode is switched from the first control mode to the second control mode, the threshold value is changed to a value larger than the value in the first control mode, and A process of changing the threshold value to a value smaller than the value in the second control mode when the control mode is switched from the second control mode to the first control mode.

5. A notification method for providing notification to a driver of a vehicle, the vehicle being equipped with an automatic driving system that performs speed control so that an actual speed follows a target speed, the notification method comprising providing notification to the driver of the vehicle when a speed error between the target speed and the actual speed exceeds a threshold value, wherein: The control mode of the speed control includes a first control mode in which the actual speed is caused to follow the target speed by actively using the brake, and a second control mode in which the actual speed is caused to follow the target speed while suppressing the use of the brake; and The notification method further includes: When the control mode is switched from the first control mode to the second control mode, the threshold value is changed to a value larger than the value in the first control mode, and When the control mode is switched from the second control mode to the first control mode, the threshold value is changed to a value smaller than the value in the second control mode.

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